Apparatus for simultaneous cleaning of a liquid and a gas

ABSTRACT

An apparatus for simultaneous cleaning of a liquid and a gas includes a centrifugal rotor delimiting in a casing a separation chamber that is arranged for through flow and cleaning of the liquid. On the outside of the casing separation discs are mounted for rotation with the centrifugal rotor. Between the separation discs there are formed axially extending separation passages formed for through flow and cleaning of the gas.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is entitled to the benefit of and incorporatesby reference essential subject matter disclosed in International PatentApplication No. PCT/SE02/01971 filed on Oct. 30, 2002 and Swedish PatentApplication No. 0103631-8 filed on Nov. 1, 2001.

FIELD OF THE INVENTION

[0002] The present invention relates to an apparatus for simultaneouscleaning of a liquid from first particles suspended therein and cleaningof a gas from second particles suspended therein. The apparatus includesa centrifugal rotor that is rotatable about a rotational axis and thatdelimits a separation chamber arranged for through flow and cleaning ofsaid liquid, a driving device for rotation of the centrifugal rotorabout said rotational axis and a gas cleaning device that is connectedwith the centrifugal rotor for rotation together therewith and that isarranged for through flow and cleaning of said gas.

BACKGROUND OF THE INVENTION

[0003] A previously known apparatus of this kind is shown and describedin WO 99/56883. In this case the centrifugal rotor supports a gascleaning device that includes both a number of conical separation discsrotatable with the centrifugal rotor and a number of stationary conicalseparations discs. The stationary separation discs are arranged betweenthe rotatable separation discs. The gas cleaning device has a gas inletfor the gas to be cleaned formed in a rotatable housing, that supportsthe rotatable separation discs on its inside, and a gas outlet forcleaned gas formed as a stationary central tub, which on its outsidesupports the stationary separation discs. An apparatus designed in thisway is relatively expensive to manufacture. Particularly the conicalseparation discs are expensive.

[0004] Another known apparatus of the defined kind is shown anddescribed in the Japanese patent application no. 11087568 (PublicationNumber 20002 79851 A). In this case a centrifugal rotor delimits arelatively large, peripherally arranged separation chamber for cleaningof liquid and a relatively small, centrally arranged separation chamberfor cleaning of gas. An apparatus designed in this way has a relativelypoor gas cleaning efficiency. The available separation space in thecentrifugal rotor for gas to be cleaned is relatively small and is, inaddition thereto, situated relatively dose to the rotational axis of thecentrifugal rotor.

[0005] A further known apparatus intended for simultaneous cleaning of aliquid and a gas is shown and described in DE 43 11 906 A1. In this casethe centrifugal rotor is completely without special members for the gascleaning. The gas to be cleaned is to be brought into rotation by thecentrifugal rotor by being introduced into a narrow gap between thecentrifugal rotor and a stationary housing surrounding the latter. Evenan apparatus designed in this way has a relatively poor gas cleaningefficiency.

[0006] The object of the present invention is to provide an apparatusfor accomplishing continuous cleaning of both a liquid and a gas, saidapparatus having a good gas cleaning efficiency and being relativelyinexpensive to manufacture.

SUMMARY OF THE INVENTION

[0007] These objects may be obtained by an apparatus of the initiallydefined kind, which is characterized in that the gas cleaning deviceincludes several separation discs distributed about said rotationalaxis, that the separation discs are arranged radially and/or axiallyoutside said separation chamber and that each of the separation discsextends axially in relation to the rotational axis, so that theseparation discs form between themselves axially extending separationpassages for through flow of said gas.

[0008] Separation discs of this kind may be produced relativelyinexpensively and be formed so that they effectively clean a gas causedto flow through the passages between themselves. Furthermore, a gascleaning device having separation discs of this kind may be maderelatively compact. By axially extending separation passages is meant inthis connection that the separation passages shall conduct the gas to becleaned either completely in parallel with the rotational axis of thecentrifugal rotor or somewhat obliquely in relation there to.

[0009] For obtainment of an efficient cleaning of the gas it isadvantageous if the separation discs extend in a direction from saidrotational axis in a way such that each one of the separation passagesbetween the discs crosses at least one imaginary radius starting fromthe rotational axis. If desired, the separation discs may be madecompletely planar but preferably they are formed so that they extendarcuately from the rotational axis.

[0010] If desired, said separation discs may by arranged in a gasseparation chamber having a surrounding wall that constitutes part ofthe rotor. Such a gas separation chamber is situated radially and/oraxially outside the previously mentioned liquid separation chamber,which is delimited by a casing of the rotor and is arranged for throughflow and cleaning of said liquid. Preferably, however, the separationdiscs are arranged in a way such that the separation passages betweenthe separation discs are open radially outwardly, seen from therotational axis of the rotor. Thereby, particles separated from the gasmay easily be thrown away from the rotor, which is thereby automaticallykept dean from such particles.

[0011] One advantage of having the separation discs arranged radiallyoutside the liquid separation chamber of the rotor is that they willoperate at a relatively large distance from the rotational axis of therotor and, thereby, provide a relatively good separation efficiency. Onthe other hand, an arrangement of this kind requires relatively muchenergy for the rotor rotation. If the separation discs are arrangedaxially on one side of the liquid separation chamber, they can be givena relatively large radial extension and a correspondingly relativelysmall axial extension.

[0012] Advantageously the centrifugal rotor is arranged in a stationaryhousing, which delimits a through flow channel for the gas to becleaned. If the separation discs are arranged radially outside theliquid separation chamber, the main part of the through flow channelpreferably is formed by radially outwardly open separation passagesbetween the separation discs. If instead the separation discs arearranged axially on one side of the liquid separation chamber, thethrough flow channel may form a supply channel to the separationpassages, which extends around the whole of the rotor.

[0013] For certain separation cases it may be suitable to form theseparation passages in a way such that their inlets for gas to becleaned are situated at a radial level closer to the rotor rotationalaxis than that at which the outlets of the passages ewe situated.Thereby, due to the rotation of the rotor, the separation discs willcreate a pumping effect on the gas flowing through the separationpassages. This means that the gas to be cleaned will be sucked into thecleaning device and, therefore, will not have to be supplied thereto atan over pressure.

[0014] The centrifugal rotor at the cleaning device according to theinvention—may be driven by any suitable means. Thus, it may be driven bymeans of an electrical, hydraulical or pneumatical motor.Advantageously, it may be driven by means of a turbine of one kind oranother. According to a preferred embodiment of the invention thecentrifugal rotor is arranged to be driven by means of an overpressureof a liquid supplied thereto, such liquid being caused to leave thecentrifugal rotor through one or more nozzles situated at a distancefrom the rotational axis of the rotor and directed in thecircumferential direction of the rotor. The centrifugal rotor in thiscase is driven by the reaction forces from the liquid, e.g. cleanedliquid, leaving the rotor through said nozzles.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The invention is described in the following with reference to theaccompanying drawings, in which FIG. 1 shows a first embodiment of theinvention,

[0016]FIG. 2 shows a section along the line II-II in FIG. 1,

[0017]FIG. 3 shows a second embodiment of the invention and

[0018]FIGS. 4 and 5 show sections along the lines IV-IV and V-V,respectively, in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The FIGS. 1 and 2 show a first embodiment of an apparatus forsimultaneous cleaning of a liquid and a gas. The apparatus includes astationary housing 1, which has an inlet 2 for liquid to be cleaned andan inlet 3 for gas to be cleaned. The liquid can be constituted bylubricating oil circulating through an internal combustion engine duringits operation, and the gas can be constituted by crankcase gas comingfrom the same combustion engine. The lubricating oil includes amongother things soot particles to be separated, and the crankcase gasincludes a mixture of soot particles and oil particles to be separated.The housing 1 has a separate outlet 4 for cleaned gas, whereas saidinlet 3 for gas to be cleaned also serves as an outlet for cleanedliquid.

[0020] Within the housing 1 a centrifugal rotor 5 is arranged to rotatearound a vertical centre axis 6. The rotor 5 is supported in twobearings 7 and 8 by a central stationary column 9, that is fixed at itslower part and at its upper part relative to the housing 1.

[0021] The rotor 5 includes a casing consisting of a surrounding wall 10a, an upper end wall 10 b and a lower end wall 10 c. Furthermore, therotor 5 includes a tubular member 11 extending centrally through thecasing 10 a-c and supporting the same. A locking ring 12 is threaded onto the upper most part of the member 11 and keeps the casing fixedrelative to the member 11. Within the rotor a separation chamber 13 forcleaning of said liquid is delimited. For passage of the liquid into theseparation chamber 13 the liquid inlet 2 of the housing 1 communicateswith a central channel 14 in a lower tubular part of the stationarycolumn 9. The column 9, the outer diameter of which is somewhat smallerthan the inner diameter of the rotatable tubular member 11, formsbetween itself and the member 11 an inlet channel 15 annular in crosssection. This inlet channel 15 communicates at its lower part throughopenings 16 in the column with the central channel 14 thereof and at itsupper part with the separation chamber 13 through openings 17 in thetubular member 11.

[0022] Within the separation chamber 13 the tubular member 11 supportson its outside a package of separation discs 18 distributed about thecentre axis 6. Each disc extends both axially and from a first radiallevel to a second radial level in the rotor, situated at differentdistances from the centre axis 6 of the rotor. The discs 18 form anangle with radii drawn from the central axis 6 of the rotor. Between thediscs 18 there are formed axially extending separation passages forthrough flow of liquid in the way illustrated by means of arrows in theseparation chamber 13.

[0023] At its lower part the rotor 5 has two outlet openings 19 (onlyone of these can be seen from FIG. 1), which are spaced from the rotorcentre axis 6 and are directed substantially tangentially in relation toa circle line drawn therethrough and coaxially with the centre axis 6.

[0024] For a more detailed description of the separation discs 18 andtheir arrangement in the rotor reference is made to WO 99/51353. Anyother different kind of separation means than the separation discs shownhere may be used in the rotor in according to the invention. Thus, theinvention is not limited to any particular separation means within therotor for cleaning of said liquid. Separation discs of another kind thatcan be used are conventional conical separation discs stacked upon eachother in the separation chamber concentrically with the centre axis ofthe rotor.

[0025] On its outside the surrounding wall 10 a of the rotor casingcarries further separation discs 20 evenly distributed about the centreaxis of the rotor. The separation discs 20 extend axially as well asfrom the casing a distance towards said stationary housing 1. As can beseen from FIG. 2 the discs 20 extend obliquely in relation to radiidrawn from the centre axis of the rotor towards the housing 1. Betweenthe discs 20 there are formed separation passages 21 (see FIG. 2), whichlike the discs 20 extend substantially across the whole axial length ofthe rotor. Several annular members 22 extend about the whole of therotor 5 at different axial levels and keep the discs in place relativeto each other and relative to the rotor. These bands fill almost but notcompletely the space between the discs 20 and the inside of thestationary housing 1, so that gas to be cleaned is forced to flow mainlythrough said separation passages 21 and not radially outside the discs20. The discs 18 within the rotor may be formed in the same way as thediscs 20.

[0026] The apparatus according to FIGS. 1 and 2 operates in followingmanner.

[0027] Liquid to be cleaned is supplied at an overpressure through theinlet 2 in the housing 1 and is conducted further on through the channel14 and the openings 16 and 17 into the upper part of the separationchamber 13. Within the separation chamber 13 the liquid is conducteddownwardly between the separation discs 18 towards and out through therotor outlets 19. At its outflow through these outlets 19 the liquidgenerates a reaction force causing and keeping the rotor in rotationabout the centre axis 6. Through the action of the centrifugal force theliquid while flowing between the separation discs 18 is freed frompartides suspended in the liquid and having a larger density than that.The particles first deposit on the separation discs and then slide tothe radially outermost edges thereof, from where they are moved bycentrifugal force further radially outwardly until they reach anddeposit on the inside of the rotor casing. The liquid freed fromparticles leaves the rotor through the outlet openings 19 and flowsfurther out of the housing 1 through a bottom outlet formed by the inlet3 of the housing 1 for gas to be cleaned.

[0028] The gas to be cleaned enters, as already mentioned, through thegas inlet 3 of the housing 1 and is conducted upwardly and axiallythrough the passages 21 between the separation discs 20 on the outsideof the rotor casing 5. As a consequence of the rotation of the rotor 5particles suspended in and having a larger density than the gas areseparated from the gas in these passages. The particles first deposit onthe separation discs 20 and thereafter slide thereon to their radiallyoutermost edges. From here they are thrown away from the rotor and hitthe inside of the stationary housing 1. By gravity the separatedparticles move downwardly to the lower part of the interior of thehousing 1. Since the embodiment of the apparatus according to theinvention shown here is intended for freeing crankcase gas from amongother things oil mist, it is presumed that the particles thus separatedfrom the gas will coalesce and that the formed liquid will run out ofthe housing 1 through its bottom outlet 3. If the particles to beseparated from the gas are dry, the bottom part of the housing 1 ispreferably made conical and tapering downwardly towards the bottomoutlet 3.

[0029] The cleaned gas flows upwardly in the housing 1 and leaves itthrough the gas outlet 4.

[0030] If the liquid being cleaned is constituted by lubricating oilcirculating in a combustion engine, and the gas being cleaned comes fromthe crankcase of the same combustion engine, both the lubricating oilcleaned in the rotor and the lubricating oil separated from thecrankcase gas may be re-conducted from the housing 1 through the gasinlet/liquid outlet 3 to said crankcase.

[0031] The FIGS. 3-5 show a second embodiment of an apparatus forsimultaneous cleaning of a liquid and a gas. This embodiment issubstantially the same as the first embodiment with regard to the partsof the latter carrying the reference numerals 1-19. The same referencenumerals have been used in the second embodiment for correspondingdetails.

[0032] The differences between the two embodiments are to be found inparts which are intended for the gas cleaning. Thus, the embodiment inthe FIGS. 3-5 has a first cleaning device 23 placed on the outside ofthe surrounding wall 10 a of the rotor casing and a second cleaningdevice 24 placed on top of the upper end wall 10 b of the rotor casing.

[0033] The cleanings device 23 covering only a limited lower part of thesurrounding wall 10 a is shown more in detail in FIG. 4. It includes aninner annular sleeve 25, that abuts against the surrounding wall 10 a,and an outer annular sleeve 26 having a larger diameter than the sleeve25. A lot of adulate wings or blades 27 extending between the sleeves 25and 26 are evenly distributed about the centre axis 6 of the rotor anddelimit between themselves passages 28 extending substantially axially.The sleeves 25, 26 and the wings 27 are preferably formed in one piece.

[0034] By means of on, the friction forces or by means of glue or insome other way the cleaning device 23 is fastened to the surroundingwall 10 a for rotation together with the rotor 5 in the housing 1. Asmall interspace is present between the cleaning device 23 and thehousing 1.

[0035] The cleaning device 24, that is kept fixed to the central tubularmember 11 of the rotor by means of a locking ring 29, includes a lowerwall 30 and an upper wall 31, both extending about the centre axis 6 ofthe rotor axially spaced from each other. A large number of separationdiscs 32 are arranged between the walls 30 and 31. These discs extendboth axially from the one wall 30 to the other wall 31 and arcuatelyfrom said locking ring 29 and outwardly towards the surrounding wall ofthe stationary housing 1. The discs 32 are evenly distributed about thecentre axis 6 of the rotor and form between themselves passages 33intended for through flow of gas to be cleaned. Two annular members 34and 35 extend about the discs 32 and almost fills out a space betweenthe discs 32 and the surrounding stationary housing 1. A certain play isleft between the members 34, 35 and the housing 1.

[0036] As can be seen from FIG. 3, the walls 30 and 31 are formed in away such that they leave between th6r respective radially inner portionsan annular opening 36. In a corresponding way an annular opening 37 isformed between the radially outermost portion of the upper wall 31 andthe upper annular member 35. The opening 37 is situated at a largerdistance from the centre axis 6 of the rotor than is the opening 36. Bythis configuration of the walls 30 and 31, the discs 32 and the annularmembers 34 and 35, the gas to be cleaned is forced to flow through thepassages 33 from the opening 36 to the opening 37, whereas gas flowradially outside the cleaning device 24 is substantially prevented.

[0037] The apparatus according to FIGS. 3-5 operates with respect to thecleaning of liquid exactly in the same way as the apparatus according tothe FIGS. 1 and 2. With respect to the cleaning of gas the apparatusaccording to the FIGS. 3-5 operates in the following manner.

[0038] Gas to be cleaned enters through the gas inlet 3 of the housing 1and is conducted upwardly through the passages 28 in the cleaning device23. By the wings 27 the gas is brought into rotation together with therotor 5 so that centrifugal force will act on the gas and particlessuspended therein. The gas flows further under rotation upwardly in theinterspace between the rotor 5 and the stationary housing 1. In thepassages 28 as well as in the interspace between the rotor 5 and thehousing 1 some partides are separated from the through flowing gas as aconsequence of the centrifugal force. Such particles deposit on theinside of the housing 1 and move gradually downwardly by gravity. Thegas flows further upwardly and through the passages 33 in the uppercleaning device 24.

[0039] The cleaning device 24 is substantially more efficient than thecleaning device 23, the latter operating only as a pre-separator forseparating relatively large particles from the gas. While the gas isflowing through the passages 33 in the cleaning device 24 it is freedfrom remaining particles. These first deposit on the adulate separationdiscs 42 and then slide thereon radially outwardly to the radiallyoutermost edges of the discs. From there the particles are thrown awayfrom the discs 32 and deposit on the stationary housing 1 between thetwo aforementioned annular members 34, 35. On the inside of the housing1 the particles move downwardly past the whole of the rotor 5 andafterwards pass out through the bottom outlet 3.

[0040] Since the cleaning device 24 has its as outlet 37 situated at alarger radius than its gas inlet 36, the separation discs 32 uponrotation of the rotor 5 will act as a fan or pump. Hereby, gas to becleaned will be sucked in through the gas inlet 3 and further upwardlyto and into the cleaning device 24, and at a certain raised pressure,will be pressed out of the housing 1 through the gas outlet 4. The gasto be cleaned, therefore, need not be supplied to the cleaning device atan over pressure. The just described suction elect of the separatordiscs can be increased somewhat if an annular stationary partition,suitably supported by the housing 1, extends from the surrounding wallof the housing inwardly towards the rotational axis 6 of the rotor tothe gas inlet 36 in the interspace between the wall 30 and the upper endwall 10 b of the rotor casing.

1-14. (Canceled)
 15. An apparatus for simultaneous cleaning of a liquidfrom first particles suspended therein and cleaning of a gas from secondparticles suspended therein, including a centrifugal rotor, that isrotatable about a rotational axis and that delimits a separation chamberarranged for through flow and cleaning of said liquid, a driving devicefor rotation of the centrifugal rotor about said rotational axis and agas cleaning device, that is connected with the centrifugal rotor forrotation together therewith and that is arranged for through flow andcleaning of said gas, wherein the gas cleaning device includes severalseparation discs distributed about said rotational axis, the separationdiscs are placed in at least one of a radial and axial orientationoutside said separation chamber and each of the separation discs extendsaxially in relation to the rotational axis, so that the separation discsform between themselves axially extending separation passages forthrough flow of said gas.
 16. An apparatus according to claim 15,wherein at least a part of the separation passages are open radiallyoutwardly, seen from the rotational axis of the centrifugal rotor. 17.An apparatus according to claim 15, wherein the separation discs extendin a direction from said rotational axis in a way such that each of theseparation passages cross at least one imaginary radius starting fromthe rotational axis.
 18. An apparatus according to claim 17, wherein theseparation discs extend arcuately in a direction from the rotationalaxis.
 19. An apparatus according to claim 15, wherein the centrifugalrotor has a casing, which delimits said separation chamber for cleaningof liquid and which on its outside supports the separation discs.
 20. Anapparatus according to claim 15, wherein the centrifugal rotor isarranged in a stationary housing and a through flow channel for said gasto be cleaned is delimited between the centrifugal rotor and thestationary housing.
 21. An apparatus according to claim 20, wherein atleast a part of said through flow channel is formed by said separationpassages.
 22. An apparatus according to claim 20, wherein at least apart of said through flow channel forms a supply channel for conductingthe gas to be cleaned to at least some of said separation passages. 23.An apparatus according to claim 22, wherein the separation passages haveinlets and outlets, the inlets being situated closer to the rotationalaxis of the centrifugal rotor than the outlets.
 24. An apparatusaccording to claim 15, wherein the driving device for rotation of thecentrifugal rotor includes a pressure fluid source and a turbine devicearranged for rotation of the centrifugal rotor by means of pressurefluid from the pressure fluid source.
 25. An apparatus according toclaim 24, wherein the centrifugal rotor is arranged for receiving saidpressure fluid and is provided with at least one outlet opening forreleasing said pressure fluid at a distance from said rotational axis ina way such that the centrifugal rotor is subjected to a rotationalforce.
 26. An apparatus according to claim 25, wherein the pressurefluid source is a source of pressurized liquid.
 27. An apparatusaccording to claim 26, wherein the liquid in said pressure fluid sourceis constituted by liquid to be cleaned in the centrifugal rotor.
 28. Anapparatus according to claim 27, which for receiving said liquid to becleaned communicates with a space, that contains lubricating oil comingfrom an internal combustion engine, and for receiving said gas to becleaned communicates with a space that contains crankcase gas comingfrom said combustion engine.